The invention relates to methods for controlling a power-dividing transmission, which comprises an adjustable hydrostat unit, a summating planet transmission with at least two outputs, and a downstream motion gear transmission designed as a dual planet transmission, and in which n stages follow one another at synchronous points at which clutches are connected, in which the at least two outputs are connectable to the motion gear transmission via a first clutch or a second clutch and an element of the motion gear transmission is adjustable via a third clutch, and further clutches for further motion gears are provided at the off-take side of the motion gear transmission.
In such transmissions (in the form in which they are known, for example, from EP 386 214 B) the control ensures that in the event of a change in the speed a motion gear change is undertaken in each case at the correct moment. If the change in speed takes place so rapidly that the control is unable to follow (for example in the case of emergency braking), the clutch of the just selected motion gear must be disengaged, in order to prevent the engine from stalling. If the emergency braking is continued until the vehicle is at a standstill, the transmission is brought into the normal position, and the vehicle is able to start off in the first motion gear.
If the emergency braking is not continued until the vehicle is at a standstill then, in the higher motion gears, synchronization of the disengaged clutch is possible by adjustment of the hydrostat. However, in most cases emergency braking is performed almost to standstill. In these circumstances, synchronization is no longer possible, since all clutches must be disengaged. The transmission is situated in an undefined switching position, in which initial synchronization of the first clutch (K1) to be engaged for the lowest gear is not possible. Thus, it is necessary to brake to complete standstill in order to be able to accelerate again. Another undefined switching position is present if, when the gear selector lever is in the neutral position, the vehicle starts to move for example on a slope. In these circumstances as well, according to the prior art it is not possible to engage a motion gear.
Accordingly, the object of the invention is to specify a method of control which in all circumstances ensures the engagement of a motion gear suitable for the instantaneous speed of travel without prior standstill, if an interruption of the power transmission has preceded.